Convert 6 chinese font ponts to include with .CURDIR
These ports were including chinese/ttfm/Makefile.ttf using an absolute
path using PORTSDIR instead of a relative one using .CURDIR. In
specific use cases, PORTSDIR will fail but .CURDIR always works. As
a bonus, this allows <pre> & <post> inclusions to be removed as well.
Covered by an old blanket permission (bapt) but only two of these ports
have maintainers anyway.